2of19Trump vs. Gavin Newsom: All the times our president has fought with our governorHealth care At a rally in Billings, Mont., in September, President Donald Trump said of then-gubernatorial candidate Gavin Newsom, "He just announced that he wants to open borders, and he wants to let anybody come in that wants to. And then he wants to pay for all medical, all school."

Trump then joked, "I may even move to California to get free health care!" See Newsom's response >>>Photo: Susan Walsh, Associated Press

3of19Gavin Newsom responded to Trump on Twitter saying, "Hey @realDonaldTrump -- Next time you call me and my policies out, have the guts to @ me and we can have a chat."

4of19Name callingA few weeks later, Trump brought up Newsom at a rally in Las Vegas, calling him a "clown."
"Democrats want to give welfare and free health care to illegal aliens," Trump said. "How about this clown in California who's running for governor? He wants open borders and then he wants to give them health care, education, everything."Photo: MANDEL NGAN;Mandel Ngan / AFP / Getty Images

5of19The "clown" thing may have struck a cord. "lol, hi @realDonaldTrump. Interesting description from the guy who is literally locking up kids like Pennywise," Newsom responded on Twitter.
Read the full story.Photo: Brooke Palmer, Warner Bros. Entertainment

6of19ImmigrationAt another rally in Johnson City, Tenn., Trump said, "Look at what's going on in California. You have a man running for governor in California who says we don't want any borders, we don't want ICE, we do want sanctuary cities."Photo: Mark Humphrey, AP

7of19Gavin Newsom responded on Twitter (again), and suggested the president focus on other, more important matters. Read the full story.Photo: Twitter / Gavin Newsom

9of19Gavin Newsom tweeted back, pointing out the fact that no Californians appeared to be rioting, over sanctuary cities or anything else. Photo: Twitter / Gavin Newsom

10of19WildfiresIn a baffling tweet in August 2018, President Trump implied California wasn't doing enough to combat wildfires.
"California wildfires are being magnified & made so much worse by the bad environmental laws which aren’t allowing massive amounts of readily available water to be properly utilized. It is being diverted into the Pacific Ocean. Must also tree clear to stop fire from spreading!"
Wildfire and water experts had no idea what he was talking about. Newsom didn't respond directly on Twitter this time, but his campaign manager Rhys Williams did: “Has anybody seen the baby’s pacifier? He dropped it again.”Photo: Ringo H.W. Chiu / Associated Press

11of19Border securityGavin Newsom also attacked President Trump after he said that any rocks thrown along the U.S.-Mexico border would be considered firearms.
"Anybody throwing stones, rocks, like they did to Mexico ... we will consider that a firearm. Because there's not much difference when you get hit in the face with a rock."Photo: Twitter / Gavin Newsom

12of19Climate change"Trump claimed last night that climate change is not man-made, is too expensive to fix, and accused scientists of having a 'political agenda.' This isn't ignorance -- this is the purposeful dismissal of factual evidence and science. And it's dangerous," Newsom tweeted on Oct. 15, 2018.Photo: Chris Pietsch, Associated Press

13of19LGBTQ IssuesHere's an old one. In July 2016, while Donald Trump was running for president, Newsom challenged his record on LGBTQ issues. Photo: Twitter / Gavin Newsom

14of19The California gubernatorial raceFollowing the gubernatorial primary, President Trump tweeted congratulations for Republican John Cox as he advanced to face Newsom in the November election.
Newsom responded, "Please come campaign for him as much as possible." Photo: Twitter / Donald Trump

15of19ImpeachmentIn June 2017, Gavin Newsom told the Bay Area News Group that he believed Congress should begin impeachment proceedings against the president. Photo: Russell Yip, The Chronicle

16of19The deficitNewsom tweeted out a short video clip of Trump saying, "The whole world is going to go to California and they owe about 15 zillion dollars. They owe more money than anybody even knows."
Newsom responded, "When the guy who increased our nation's deficit by a trillion dollars -- to line the pockets of billionaires -- tries to give you debt advice... HARD PASS."Photo: Twitter / Gavin Newsom

17of19Gas taxApparently, Trump criticized California's recently passed gas tax to pay for road and transit improvements, because Newsom found it necessary to point out Trump had in the past endorsed a 25-cent nationwide gas tax. Photo: Twitter / Gavin Newsom

18of19Family separationNewsom tweeted of the Trump administration's controversial family separation policy, "This makes my blood boil -- there is NOTHING 'incredible' about ripping children away from their families and putting them in cages. Your policy was not only an epic failure, but an abomination. A stain on our nation’s history. We will not let you forget that, @realDonaldTrump." Photo: Associated Press

Candidate Gavin Newsom promised the people of California that he would get them universal health care. Gov. Gavin Newsom is not going to fulfill that promise. And that’s fine. He won’t be the first politician to make a commitment on the campaign trail that didn’t happen once he took office. He certainly won’t be the last

During his campaign, Newsom’s most ambitious commitment was to provide health care to all Californians through a government-run, single-payer system. This declaration allowed him to separate himself from the other Democrats in the race, making him not just the early front-runner, but also the preferred candidate for the party’s energized progressive base. His most prominent opponent, former Los Angeles Mayor Antonio Villaraigosa, dismissed Newsom’s goal as “snake oil,” but it’s entirely possible that Newsom would not have been elected without making such a pledge.

Newsom talked stirringly about “bolder colors and bigger ideas.” But for those who listened closely, Newsom’s language became more measured as his lead in the polls grew. Words like “inevitably” and “ultimately” began to creep into his conversation. He told The Chronicle last spring that single-payer “is not an act that would occur by the signature of the next governor,” at least theoretically extending the timeline beyond the end of his second term in 2027. “There’s a lot of mythology about that,” he added.

Words like “mythology” rarely make it onto campaign bumper stickers, and so it appears that Newsom is subtly trying to prepare his supporters that while universal health care may be a worthwhile objective, it is not going to become a reality in California in the foreseeable future. It may be wise to mark the arrival for Newsom’s single-payer health care plan on the calendar for the same week as completion of Jerry Brown’s high-speed rail, Donald Trump’s border wall, and Colin Kaepernick’s induction into the Pro Football Hall of Fame.

The obstacles that will prevent Newsom from keeping his word are far beyond his control. The federal government would need to go along with such a plan, and neither the Trump administration nor a Republican-led Senate is likely to sign off. (Even a Democratic-controlled House would be a challenge: There are a lot of members elected in swing state districts that Trump carried in 2016 who may not want to defend a vote like this one.)

The other large-scale problem for a single-payer system is the sheer financial cost. Last year’s legislation that would have implemented such a plan carried a price of roughly $400 billion. The most optimistic projections predict that half of that money would come from existing federal, state and local government programs. But this would still require tax increases on a scale never before seen in California — or anywhere else. Newsom has now begun to refer to himself as “the adult in the room,” which suggests that he is not interested in budget-busting on such a grand scale.

Through no fault of his own, Newsom will never achieve his audacious goal. But he still intends to spend tremendous amounts of government money on a more generous health care system for Californians. Even in the face of a likely economic downturn, he will move forward with expansive and expensive programs to extend coverage to more state residents.

But that won’t be enough for many of his supporters. Voters tend to hear what they want to hear, and his most progressive backers will not back down simply because their candidate has. The California Nurses Association has been an aggressive and savvy advocate for a single-payer system for years, and it intends to apply maximum pressure on Newsom to fulfill his commitment — right now.

The question then becomes what his allies will accept as a reasonable compromise. There are already heightened expectations that Newsom will expand Medi-Cal services for undocumented immigrants, and take steps to shore up the state’s health exchanges and subsidize prescription drug costs. These would represent much larger expenditures than Brown was ever willing to make, but it’s still a long way from universal coverage. They will almost certainly want much more from the new governor in exchange for their continued support.

Newsom ran on a slogan of “Courage for a Change,” so the new governor may want to consider a display of bravery in which he levels with the Californians who actually believed his campaign promise.

Dan Schnur teaches at the University of Southern California’s Annenberg School of Communications and UC Berkeley’s Institute of Governmental Studies.